Abstract：This paper simulates transmittance of neutrons，whose energy is 14．5MeV，in polyethylene， graphite，steel，non-uniform materials of steel and polyethylene with Monte Carlo method．The consistency of the simulative results and the theory of radiation protection validate the correctness．In addition，we conclude that the shielding effect which the heavier nuclei materials are before the lighter nuclei is much better than that of the singe materials or the lighter nuclei materials in the former under certain conditions．
2012, Vol. 1 